You could have blue balls. Medically speaking, there is a condition the causes pain in the testicles—more on that in a second. But, realistically, you are probably fine, just frustrated that you didn't ejaculate. Which is understandable—sex is great. It's just that non-ejaculation isn't a serious medical condition—a condition that is fairly un-researched, we should add. Saying you have "blue balls" comes off a little whiney. And now we're imagining your blue balls.

If you experience pain in your testicles prior to ejaculation, this is probably due to the blood that flows to the penis and scrotum upon arousal building up and stretching the tubes, putting pressure on the testicles. The moniker refers to the blue tint of testicles when they absorb some of the oxygen from the trapped blood, or because the blood itself develops a blue-ish hinge from lack of oxygen (because it isn't circulating), according to University of California, Santa Barbara.

Again, the science behind blue balls is limited, despite its common colloquial usage. It should be noted that women, too, can experience pooling blood in their genitals, leading to "blue clit" or "blue vulva."